Strange issue with no audio on a track.

I hope someone can help, I’ve been using Cubase/Nuendo for years but this one has stumped me:

I have an instrument track (retrologue) on which the meter shows level. The audio is routed to stereo out the same as other audible tracks, other tracks work fine.

If I open up the edit window for the midi on the instrument track, suddenly I can hear it fine. Close the window, the audio goes away. If I select rec or monitor on the track, the audio comes back.

I’ve tried removing and disabling plugins, no dice. What I don’t understand is that there is level on the track meter but not on the stereo output meter. I’ve tried routing it to a group track to see if level makes it to that track, it doesn’t. Nor is level making it to an FX track.

This is strange behavior, hope someone can help!

After some more digging … ASIO Guard is causing this, WTF?

Disabling it returns everything to normal.